#include<stdio.h>
#include<math.h>

int main (void)
{
	int n,sum,i;
	sum = 0;
	
	printf("Enter n:");
	scanf("%d",&n);
	
	for (i=1;i<=n;i++)
	{
		sum = sum + pow(2,i);
	}
	
	printf("sum=%d",sum);
	
	return 0;
}
